I just had my aerobic septic system pumped on Wednesday of this week (after 11 years). Since it is four tanks (raw, aeration, filter/treatment, and sump - about 1500 gal) the cost was $300. This company usually charges $325, but they gave me a $25 discount because the driver and truck are actually based close to my house and they had such a short drive to get here. I called around 10 AM and they were here by 12:30 PM on the same day.
My aerobic inspector had told me that solids were starting to get into the filter area and sump. The clean water sump had maybe 6" of sludge in the bottom and the filter was starting to have a little brown sludge collect on it. The pumper truck was concerned about driving over the line between my sprinkler heads, so he stopped the truck and strung an extra hose section to the tanks. It was a very easy approach for the truck with no trees and firm ground. The guys on the truck said my system needed pumping, but it was very clean with absolutely no grease or other trash in my tanks. Actually, in the clean water sump, there was a cow insect ear tag that fell into the water. I tie tags just inside the tank access covers and it keeps fire ants away. Somehow the tag got loose and dropped into the tank. They sucked it up without a hitch. The guys went out of their way to backwash the tanks and get all the sludge. I gave them a fresh water hose with spray nozzle and they used that to help too. They were careful to keep sludge out of my yard and and not leave any stinky mess. I really appreciated the job they did, so I gave them each a $10 gratuity and thanked them for the great job.
I have a sign that I love to put in my bathrooms near the commode, but my wife won't let me put it up. The sign says, "Don't put anything into the toilet that you haven't eaten." That pretty much wraps up my theory of keeping a septic system healthy. I run my laundry water out as gray water and don't put that through the tanks. That helps keep the bacteria high and the soap sludge low. Of course, dish water also has soap, but it can't compare to boxes and boxes of powered detergent. We use our garbage disposal too, but mostly for meal residues washed off of plates and some vegetable trimmings. Most of our prep cuttings and peelings go into the trash can. If it's greasy, it gets wiped with a towel before going into the sink or dishwasher. We collect oils/grease from cooking in a can and put that also into the trash. Not using the toilet as a trash can is a big thing. Clean wipes/baby wipes are the kinds of things that wreak havoc on a septic system. I learned that the hard way when my aerator pump started making noise and popping the breaker. I found a Clorox wipe wrapped around its shaft making it off balance and drawing excess current. It only took one careless disposal to gum up the system.